1. Field of the Invention
This invention relates to a composition for a millboard material, and more particularly, to a nonasbestos formulation for a high temperature millboard.
2. Description of the Prior Art
Millboard has come into common use over the past years for a variety of applications. For example, it can be used in gasket applications, thermal insulation and Lehr roll fabrication. Typical millboard formulations employ asbestos fiber, typically in combination with other heat resistant fibers or fillers and binders and are capable of withstanding exposure to temperatures, such as 900.degree. to 1,000.degree. F. without injury. The millboard is typically by water-laying or paper-making processes.
However, asbestos in all forms and uses has become suspect of creating health hazards during processing and to the end user. The large existing investments in processing equipment and the high cost of change dictates that substitutes for asbestos must be capable of being processed on existing equipment. The need in numerous applications for millboard to withstand high temperatures, necessitates that the substitute be predominately or entirely an inorganic fiber due to the low combustion temperature of organic fibers. While glass fiber would appear to be a reasonable substitute for asbestos fiber, processing requirements and end product properties have not been successfully fulfilled by this substitution.